Positioning aid

ABSTRACT

A positioning aid for a magnetic device used for positioning a shuttering means, the magnetic device being movable between a position of use, in which said magnetic device is in contact with a ferromagnetic shuttering support, and a position of non-use, in which said magnetic device is spaced apart from the shuttering support, said positioning aid comprising at least one retaining device relative to which the magnetic device is supported against a holding force of said magnetic device, and further comprising at least one elastic support unit for producing a lifting force against said holding force so as to hold the magnetic device in the position of non-use. In order to be able to provide such positioning aids with a more compact structural design and to use them more universally, the present invention is so conceived that the magnetic device is firmly connected to the retaining device and that, at least in the position of non-use, the support unit is arranged between the retaining device and the shuttering support, at least along certain sections thereof.

FIELD OF THE INVENTION

The present invention relates to a positioning aid for a magnetic deviceused for positioning a shuttering means, the magnetic device beingmovable between a position of use, in which said magnetic device is incontact with a ferromagnetic shuttering support, and a position ofnon-use, in which said magnetic device is spaced apart from theshuttering support, said positioning aid comprising at least oneretaining device relative to which the magnetic device is supportedagainst a holding force of said magnetic device, and further comprisingat least one elastic support unit for producing a lifting force againstsaid holding force so as to hold the magnetic device in the position ofnon-use.

BACKGROUND OF THE INVENTION

Such a positioning aid for magnetic devices used for positioning ashuttering means is known e.g. from EP 0 842 339. The magnetic deviceconsists here of a permanent magnet accommodated in a retaining device.The retaining device is integrated in shuttering parts of the shutteringsystem and is provided with a lift-off bow which extends over the magnetfrom one side to the other and which rests on the shuttering support. Aspring, which forms the support unit and which applies the lifting forceto the magnet, is located between the retaining device and the magneticdevice at a position above said magnetic device. At the position of use,the magnet is in contact with the ferromagnetic shuttering support. Dueto the holding force of the magnet on the shuttering support, adisplacement of the magnet is prevented so that the magnet can be usedfor positioning the shuttering parts on the shuttering support. Theholding force of the magnet overcomes the lifting force of the spring.If the magnet is to be displaced, the magnet is lifted off from theshuttering support by means of a lifting screw. As soon as the magnet isspaced apart from the shuttering support, the holding force applied bythe magnet to the shuttering support decreases strongly. At the positionof non-use, i.e. in the raised condition of the magnet, the liftingforce of the spring is dimensioned such that it overcomes the residualholding force between the magnet and the shuttering support and theweight of the magnet itself, so that the magnet will remain at theposition of non-use. The positioning aid can then be displaced to a newsite. For fixing the positioning aid to the shuttering support, themagnet is forced towards the shuttering support, until the holding forceand the weight of the magnet overcome the lifting force of the springand the magnet moves automatically into contact with the shutteringsupport. The force for returning the magnet from its position of non-useto the position of use can be applied e.g. by a blow on the retainingdevice.

The known positioning aid proves to entail rather a high expenditure,with regard to space requirements as well as with regard to productioncosts. In addition, it cannot be used in a flexible manner, since thefield of use is determined by the magnet provided. If finer contours areto be delimited on the shuttering support by the shuttering elements, orif strong holding forces are required for comparatively large shutteringelements, it is often impossible to use the known positioning aids.

It is therefore the object of the present invention to provide aneconomy-priced solution for positioning aids, which can be useduniversally.

SUMMARY OF THE INVENTION

The object of the present invention is achieved in that the magneticdevice is firmly connected to the retaining device and that, at least inthe position of non-use, the support unit is arranged between theretaining device and the shuttering support, at least along certainsections thereof.

This solution is simple and has the advantage that the support unit needno longer be arranged above the magnetic device, whereby theconstruction height of the positioning aid will be reducedsubstantially. The support unit can now be laterally attached to themagnetic device. This means that the field of use of the positioning aidwill no longer be limited by the structural design of the lift-off boweither. It will therefore be possible to adapt the retaining device tothe dimensions of the magnetic device.

In this connection, it may be advantageous when at least twospaced-apart retaining devices are provided, which each have associatedtherewith at least one support unit. This will allow an adaptation ofthe retaining devices to magnetic devices having different dimensions,after the fashion of a building set.

It can be of advantage when the retaining devices are arranged onopposed sides of the magnetic device. A uniform support of the magneticdevice can be realized in this way.

It may also prove to be advantageous when four retaining devices areprovided. Also this provides the possibility of realizing a uniformsupport of the magnetic device. When the magnetic device issubstantially quadrangular when seen from above, a very uniform supportof the magnetic device on all four sides thereof can be realized.Especially in the case of very long, essentially rectangular magneticdevices, a structural design of this kind may prove to be advantageousso as to avoid tilting.

According to an advantageous further development of the presentinvention, two respective retaining devices can be associated with oneside of the magnetic device. Also this provides the possibility ofrealizing a uniform support of the magnetic device. The retainingdevices can here be provided close to the corners of a magnetic device,which is quadrangular or rectangular when seen from above. It may thenbe of advantage to provide the retaining devices on the longer sides ofa magnetic device, which is rectangular when seen from above.

The retaining devices can be interconnected such that they are adaptedto be moved to spaced-apart positions via associated adjusting means, sothat said retaining devices can be mounted on and adapted to therespective magnetic devices more easily. The retaining devices can beadapted more easily to the respective magnetic devices in this way.

It may also prove to be advantageous when two retaining devices arerigidly interconnected. It will be possible to achieve a more stableconnection between the retaining devices in this way. In this case, tworespective ones of four retaining devices can be rigidly interconnected,so as to form two retaining elements.

In addition, it may prove to be advantageous when the retaining devices,together with the adjusting means, form a holding frame which surroundsthe magnetic device. Also this allows a safe connection to be realizedbetween the magnetic device and the retaining device.

In order to make the retaining devices and the magnetic device moreeasily replaceable, the retaining devices can be adapted to bereleasably connected to the magnetic device.

It may also prove to be advantageous when the magnetic device hasessentially the shape of a parallelepiped and when the bottom sidethereof faces the shuttering support. In the case of suchsimple-geometry magnetic devices, an adaptation of the retaining devicesto the magnetic device can easily be realized.

It may also be of advantage when the retaining device is adapted to beattached to one of the side faces of the magnetic device. A positioningaid having a particularly low construction height can be realized inthis way.

In special cases of use, it may also be of advantage when the retainingdevice is attached to an upper side of the magnetic device, said upperside facing away from the shuttering side.

In order to facilitate the mounting of the retaining devices on themagnetic device, said retaining devices may include reception meanswhich are engaged by the magnetic device.

In this respect, it may of advantage when the magnetic device is adaptedto be inserted into said reception means. The magnetic devices and thereception means can then simply be inserted into one another and securedin position relative to one another e.g. by simple headless screws. Thiswill make mounting much easier.

In addition, it may prove to be advantageous when the retaining deviceis attached to the magnetic device by means of a screw connection. Areliable connection between the magnetic device and the retaining devicecan be guaranteed in this way.

According to an advantageous further development of the presentinvention, a lift-off means can be provided, with the aid of which themagnetic device can be transferred from its position of use to itsposition of non-use. The magnetic device can thus be lifted off moreeasily.

It may also be of advantage, when the lift-off means is attached to themagnetic device. In this case, it will not be necessary to attach thelift-off means to the retaining device so that the structural design ofthe retaining device can be simplified. In addition, the wholepositioning aid can be rendered more compact.

A particularly simple and nevertheless effective lift-off means can beprovided, when the lift-off means comprises an eccentric which isadapted to be brought into engagement with the shuttering support, so asto transfer the magnetic device from the position of use to the positionof non-use.

In this case, it may be of advantage when a lever is provided foroperating the lift-off means. Also this allows a very simple lift-offmeans to be realized.

It may also be advantageous when the lever and the eccentric are firmlyinterconnected and rotatably supported on the magnetic device.

Furthermore, it may prove to be advantageous when the eccentric isarranged such that it is located closer to one side of the magneticdevice than to the side located opposite said first-mentioned side. Theeccentric will therefore produce an asymmetric effect when the magneticdevice is lifted off. The forces that have to be applied for lifting offthe magnetic device can be reduced in this way.

In accordance with an advantageous embodiment of the present invention,the support unit can be provided with an elastic spring element forproducing the lifting force. A very simple support unit can be realizedin this way.

According to one embodiment, the elastic spring element can be acompression spring. Compression springs allow strong forces and they areeconomy-priced components.

Alternatively, the elastic spring element can comprise an elastomer.Making use of elastomers, very simple and economy-priced spring elementscan be realized.

According to an advantageous further development, the elastomer can be arubber. Also this material is suitable for realizing permanently elasticspring elements at a reasonable price.

Alternatively, the elastic spring element can comprise a plastic spring.The support unit and the retaining device can then be designed in aweight-reducing manner.

A particularly compact structural design of the positioning aid can beachieved, when the elastic spring element is a bending sheet whose endportion is laterally spread by sliding on the shuttering support duringtransfer from the position of non-use to the position of use.

According to an advantageous further development of the presentinvention, the support unit can include a rest-on means, which isdisplaceably supported in the retaining device and which rests on theshuttering support at least at the position of non-use, the spring meansbeing accommodated between the rest-on means and the retaining device.This allows the support unit to be designed after the fashion of apiston-cylinder unit, in which the rest-on means defines a displaceablepiston.

It may by of advantage when the rest-on means is substantiallypot-shaped and when the reception means of the retaining device has theshape of a cylinder jacket. Having this kind of structural design, thereception means can simultaneously be used as a guide element for thespring means.

In order to improve the operational dependability, the rest-on means canbe captively connected to the retaining device.

In order to achieve the highest possible supporting forces, the springforce of the spring means can be adjustable. In this connection, it mayprove to be advantageous when an adjusting screw is provided foradjusting the spring force. Such a screw provides a simple possibilityof adjustment. It is also imaginable that the spring means itself isprovided with an adjusting thread. It will then be possible to carry outthe adjustment by rotating the spring means itself. The retaining devicemust in this case be provided with a reception means having a threadlikestructural design.

According to an advantageous further development of the presentinvention, the retaining device can be integrated in the magneticdevice. A particularly compact structural design comprising thepositioning aid together with the magnetic device can be realized inthis way.

In this case, it may prove to be advantageous when the retaining devicesare formed by holes in the magnetic device. This allows a very simplestructural design of the retaining device.

It may also be of advantage, when the retaining device is connected tothe magnetic device by means of an adhesive. A particularly simple andeconomy-priced structural design can be realized in this way.

According to the present invention, a building set is additionallyclaimed, which comprises a positioning aid according to the presentinvention and a magnetic device.

Likewise, a shuttering means is claimed, which is provided with apositioning aid according to the present invention.

In this respect, it may be of advantage when the shuttering means andthe retaining device are formed integrally with on another. Theretaining device can then be produced together with the shuttering meansin one operating cycle.

In addition, it may be of advantage when the magnetic device and theshuttering means are firmly interconnected. A stable and compactstructural design of the shuttering means and of the magnetic devicewill be obtained in this way. In addition, the magnet can then beanchored reliably in the shuttering means.

Furthermore, it may prove to be advantageous when, at the position ofnon-use, the shuttering means is spaced apart from the shutteringsupport. The shuttering means can then easily be displaced on ashuttering support and moved to a predetermined position. The shutteringmeans will then only rest on one or on a plurality of support units.

In order to achieve the best possible result as far as the finishedprefabricated concrete components are concerned, it may prove to beadvantageous when, at the position of use, the shuttering means and theretaining device, respectively, rest on the shuttering support.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the present invention will be explained in detailmaking reference to a plurality of embodiments.

FIG. 1 shows a first embodiment of the positioning aid according to thepresent invention in a sectional view along line I—I of FIG. 3, themagnetic device being at the position of non-use;

FIG. 2 shows the positioning aid of FIG. 1, the magnetic device being atthe position of use;

FIG. 3 shows the positioning aid of FIG. 1 in a sectional top view alongline lll—lll of FIG. 2;

FIG. 4 shows the positioning aid of FIG. 1 in a sectional view alongline IV—IV;

FIG. 5 shows the retaining device and the support unit in an enlargedrepresentation according to FIG. 1;

FIG. 6 shows the retaining device and the support unit of FIG. 5 in arepresentation according to FIG. 2;

FIG. 7 shows a second embodiment of the retaining device and of thesupport unit at the position of non-use of the magnetic device;

FIG. 8 shows the retaining device and the support unit of FIG. 8 at theposition of use of the magnetic device;

FIG. 9 shows a third embodiment of the positioning aid in a side view,the magnetic device being at the position of non-use;

FIG. 10 shows the positioning aid of FIG. 9 in a sectional view alongline X—X, the magnetic device being at the position of use;

FIG. 11 shows a sectional view of the positioning aid of FIG. 9 alongline X—X, the magnetic device being at the position of non-use;

FIG. 12 shows a fourth embodiment of the positioning aid in arepresentation corresponding to that of FIG. 1;

FIG. 13 shows the positioning aid of FIG. 12, the magnetic device beingat the position of use;

FIG. 14 shows a representation of the positioning aid of FIG. 12corresponding to the representation in FIG. 3;

FIG. 15 shows a mounting representation of the positioning aid of FIG.12;

FIG. 16 shows a fifth embodiment of the positioning aid in arepresentation corresponding to that of FIG. 1;

FIG. 17 shows the positioning aid of FIG. 16 in a mountingrepresentation;

FIG. 18 shows a sixth embodiment of a positioning aid according to therepresentation in FIG. 1;

FIG. 19 shows the embodiment of FIG. 18 in a top view;

FIG. 20 shows a seventh embodiment of the positioning aid according tothe present invention in a representation corresponding to that of FIG.1;

FIG. 21 shows a top view of the positioning aid of FIG. 20;

FIG. 22 shows a side view of the positioning aid of FIG. 20;

FIG. 23 shows an eighth embodiment of the positioning aid according tothe present invention, the positioning aid being integrated in ashuttering means and the positioning aid occupying the position ofnon-use;

FIG. 24 shows the embodiment of FIG. 23 at the position of use;

FIG. 25 shows a further embodiment of the retaining device and of thesupport unit in an enlarged representation according to FIG. 1, at theposition of non-use;

FIG. 26 shows that representation of FIG. 25 at the position of use;

FIG. 27 shows a further embodiment of the retaining device and of thesupport unit at the position of non-use in a representation according toFIG. 25;

FIG. 28 shows the retaining device and the support unit of FIG. 27 atthe position of use.

DETAILED DESCRIPTION

FIG. 1 shows a positioning aid 1 according to the present inventiontogether with a magnetic device 2 having a lift-off means 3 providedthereon. The positioning aid 1 forms together with the magnetic device 2a building set and these two components may also form a shutteringelement.

The magnetic device 2 is a permanent magnet having essentially the shapeof a parallel-epiped and comprising a substantially flat bottom side 4and an upper side 5 that is parallel to said bottom side 4 and, betweensaid upper side and said bottom side, side faces 6 which are arranged atright angles to one another. When seen from above, the magnetic deviceis substantially square in shape.

At a position of use of the magnetic device 2, the bottom side 4 of saidmagnetic device 2 is in contact with a ferromagnetic shuttering support7.

The position of use is shown in FIG. 2. At a position of non-use, theshuttering support 7 and the bottom side 4 are spaced apart, as can beseen in FIG. 1.

The upper side 5 has provided thereon a rod-like handling device 8 bymeans of which the magnetic device 2 can be displaced on the shutteringsupport 7, provided that the magnetic device 2 is at the position ofnon-use. This handling device 8 can also be used for transferring themagnetic device 2 from the position of non-use to the position of use.

One of the side faces 6 of the magnetic device 2 has provided thereon abearing pin 9, an eccentric 10, which has a lever 11 attached thereto,being pivotably rotatable on said bearing pin 9. In the representationof FIG. 1, the eccentric is in engagement with the shuttering support 7,the magnetic device 2 being in this condition transferable from itsposition of use to its position of non-use by operating the lever 11. Ascan especially be seen in the representation of FIG. 3, the bearing pin9 is located comparatively close to the left end of the associated sideface 6 so that the eccentric is adapted to be brought into engagementwith the shuttering support 7 essentially in one corner of the magneticdevice.

The magnetic device 2 has additionally attached thereto four retainingdevices 12, two respective retaining devices 12 being associated withone side face 6. The retaining devices 12 are arranged on opposed sidesof the magnetic device 2. The retaining devices 12 can be attached tothe magnetic device 2 e.g. by means of a screw connection, not shown, orby means of an adhesive. The retaining devices 12 can, in particular, bereleasably connected to the magnetic device 2. When the positioning aidis in operation, the retaining devices 12 are, however, rigidlyconnected to the magnetic device 2.

Each of the retaining devices 12 is provided with a support unit 13comprising a pot-shaped rest-on means 14 and a spring means 15. Therest-on means 14 is provided with a cylindrical outer surface 16 whichis accommodated in a cylindrical inner surface 17 of the retainingdevice 12 in an axially displaceable manner. The spring unit 15comprises an elastomeric spring element 18 made of rubber and havingrespective threaded bolts 19 and 20 at both ends thereof, the threadedbolt 19 being received in a tapped hole 21 of the rest-on means 14 andthe threaded bolt 20 being received in a tapped hole 22 of the retainingdevice 12. The rest-on means 14 and the spring element 18 are captivelyconnected to the retaining device 12 in this way.

FIG. 5 shows the support unit 13 in a condition in which the magneticdevice 2 is at a position of non-use. This has the effect that therest-on means 14 with the rest-on surface 23 projects beyond theretaining device 12. The rest-on surface 23 rests on the shutteringsupport 7 in this condition.

FIG. 6 shows a condition of the support unit 13 in which the magneticdevice 2 is at its position of use. The spring means 15 is compressed atthe position of use of the magnetic device 2.

The spring means 15 works as a compression spring, i.e. it produces alifting force which counteracts the holding force of the magnet at itsposition of use. At the position of use of the magnetic device, thelifting force is, however, much weaker than the holding force of themagnetic device. The magnetic device 2 is therefore in firm contact withthe shuttering support 7. At the position of non-use, the magneticdevice 2 is spaced apart from the shuttering support 7 so that theholding force produced by the magnet has been reduced substantially. Thelifting force applied by the spring means 15 is dimensioned such that,at the position of non-use of the shuttering support 7, the liftingforce is stronger than the residual holding force of the magnetic device2 and the weight of the magnetic device 2 so that the holding force willsuffice to hold the magnetic device 2 at the position of non-use.

The spring means may also be designed such that, at the position ofnon-use, only the rest-on means projects beyond the bottom side of themagnetic device and the spring means ends above the bottom side of themagnetic device. The spring means is then arranged only laterally of themagnetic device. Preferably, however, also the spring means should endbelow the bottom side of the magnetic device at the position of non-use.In this way, the more compact structural design of the positioning aidaccording to the present invention will be obtained.

In the following, the mode of operation of the present invention will beexplained in detail:

For producing a shuttering with shuttering elements, the positioningaid, together with the magnetic device 2, is displaced on the shutteringsupport 7 to the desired position, the magnetic device 2 occupying theposition of non-use. As soon as the desired position has been reached, apressure force acting in the direction of the shuttering support 7 isapplied to the handling device 8; this pressure force overcomes theholding force, and the magnetic device 2, together with the retainingdevice, is transferred from its position of non-use to its position ofuse. In the course of this process, the spring elements 18 in the springmeans 15 are compressed. The shuttering elements can then be connectedto the positioning aid or the magnetic device 2 so as to finish theshuttering.

For detaching the magnetic device 2, the lever 11 is operated so as torotate the eccentric 10 so that said eccentric will come into engagementwith the shuttering support 7. When the lever is moved anticlockwise inthe representations shown in FIGS. 1 and 2, the eccentric 10 willproduce a detaching force which will release the magnetic device fromthe shuttering support 7. Since the holding force decreasesdisproportionately as the distance between the magnetic device and theshuttering support 7 increases, it proves to be effective to lift firstone corner of the magnetic device 2 with the aid of the lift-off means3. This has the effect that the holding force of the magnet decreasessubstantially so that the lifting force of the spring means will sufficeto transfer the magnetic device 2 from its position of use to itsposition of non-use. The positioning aid 1, together with the magneticdevice 2, can then be displaced to some other position on the shutteringsupport 7. In the course of this process, an operator can handle thepositioning aid 1 via the handling device 8.

Due to the structural design of the retaining devices 12, thepositioning aid can be given a very compact design. In addition, due tothe fact that the retaining device 12 is designed such that it hassmooth surfaces, it offers to the user an easily discernible positioningaid. The lower edge of the retaining device 12, for example, is locatedonly slightly above the shuttering support 7 at the position of non-useof the magnetic device 2, so that the positioning aid and thus themagnetic device 2 can be positioned and aligned precisely e.g. along apredetermined line. Since a plurality of individual retaining devices 12is provided, the retaining devices can be attached to magnetic devices 2having different dimensions. It is imaginable to provide larger magneticdevices 2 with a higher number of retaining devices 12. It is alsoimaginable to provide the retaining devices 12 at different locations ofthe magnetic device 2, if this should be necessary in view of the givenspatial conditions. The retaining devices 12 can therefore be attachedto the magnetic device such that they are spaced apart more widely or ata small distance from one another. Hence, a building set can be created,which consists of magnetic devices 2 having different dimensions andstrengths and of a plurality of retaining devices 12. This allows thepositioning aid to be designed individually.

In the following, a second embodiment of the present invention will beexplained in detail making reference to FIG. 7 and FIG. 8. In order toavoid repetitions, identical elements will be designated by identicalreference numerals and only the differences existing in comparison withthe first embodiment will be explained.

In the second embodiment, compression springs 24 made of steel or ofplastic material are used instead of the spring elements 18. In FIG. 7,the retaining device with the support unit is shown in the condition inwhich the magnetic device 2 occupies the position of non-use. In FIG. 8,the magnetic device 2 occupies the position of use, so that thecompression springs 24 are compressed. The rest-on means 14 is providedwith a cover 25 having a hole 26 through which a rod-shaped member 27extends, the rod-shaped member 27 having a stop 28 provided thereon. Therod-shaped member 27 is fixedly attached to the retaining device 12 bymeans of a screw connection. The stop 28, together with the cover 25,prevents the rest-on means 14 from becoming detached from the retainingdevice 12.

FIGS. 9, 10 and 11 describe a third embodiment of the present invention.Also in this case, identical components are designated by identicalreference numerals so as to avoid repetitions. Only the differences willbe explained.

In contrast to the first embodiment, the retaining device 12 of thethird embodiment comprises plate-shaped elements 29, which are attachedto the magnetic device 2 and which accommodate between them a springsteel sheet 30 that extends vertically towards the shuttering support 7.As can be seen from FIGS. 10 and 11, end sections 31 of said springsteel sheets are laterally spread when the magnetic device is beingtransferred from its position of non-use to its position of useaccording to FIG. 10. Due to this deformation, they produce thenecessary lifting force. In so doing, the end sections 31 slide on theshuttering support 7. In the position of non-use, the retaining devicerests via the respective end sections 31 of the spring steel sheets 30on the shuttering support 7.

When the spring elements are designed in this way, the structural designin question will be very reasonable in price.

FIGS. 12, 13, 14 and 15 show a fourth embodiment of the presentinvention. The mode of operation corresponds to that of the firstembodiment. Also the spring elements are designed in the same way. Incontrast to the first embodiment, connection plates 32 and 33 are,however, provided between two respective retaining devices 12, each ofsaid connection plates 32 and 33 connecting two retaining devices 12. Acombination of connection plates 32, 33 and retaining devices 12 definesa retaining element 34. As can be seen in FIG. 15, the two retainingelements 34 can laterally be pushed onto the magnetic device 2 for thepurpose of mounting. The retaining elements 34 can be mounted on themagnetic device 2 in frictional engagement therewith by means ofheadless screws 35 which are screwed into respective tapped holes 36.The two retaining devices 12, together with the connection plates 32 and33, enclose the end sections of the magnetic device 2 in a substantiallyU-shaped configuration.

FIGS. 16 and 17 show a fifth embodiment, which is provided withretaining elements 34 as well, but in the case of which the connectionplates are replaced by retaining bridges 37 which interconnect tworespective retaining devices 12. An additional mounting plate 38 extendson the upper side 5 of the magnetic device 2 along a certain sectionthereof and can be connected to the magnetic device 2 via a hole 39 anda screw 40. Said screw 40 is located on the upper side 5 of the magneticdevice 2. Due to the structural design of the retaining bridge 37 and ofthe retaining devices 12, the retaining element 34 is in large-areacontact with the associated side face 6 of the magnetic device 2.

Also in this case compression springs are used as spring elements.

FIGS. 18 and 19 represent a sixth embodiment of the present invention.In this embodiment, the retaining device 12 is integrated in themagnetic device 2. It is formed by blind holes 41 accommodating therespective support units 13. This leads to a further compact structuraldesign of the combination of magnetic device and positioning aid. If amagnetic device having a layered structure is used, it will,alternatively, be imaginable to partially break through one of thelayers extending vertically and in the longitudinal direction, so as toform reception means for the support unit.

FIGS. 20, 21 and 22 discloses a seventh embodiment of the presentinvention whose mode of operation corresponds essentially to that of thethird embodiment. Also this embodiment is provided with spring steelsheets 30. The components used in this embodiment as a retaining elementare, however, screws 42 by means of which the spring steel sheets aremounted on the magnetic device 2.

FIGS. 23 and 24 show an eighth embodiment of the present invention. Inthis embodiment, a plurality of retaining devices is formed integrallywith a shuttering means 41. The representation in FIG. 23 is a sectionalview in which two of the retaining elements can be seen. The shutteringmeans has essentially the shape of a parallelepiped comprisingshuttering side faces 42 and a top side 43 which interconnects the twoshuttering side faces 42. The magnetic device 2 is accommodated in amagnet reception means 44. In the embodiment shown, the magnetic device2 is fixed to the magnet reception means 44 by means of an adhesive. Thebottom side 4 of the magnetic device 2 is flush with the retainingdevices and the shuttering means 41, respectively. The structural designof the support units 13 corresponds e.g. to the structural design in thecase of the first embodiment. The alternatively described embodimentscan be used as well.

At the position of use, the bottom side 4 of the magnetic device 2 andthe retaining devices and the shuttering means, respectively, rest onthe shuttering support. It follows that, at the position of non-use, theshuttering means is only supported via the support units 13. This hasthe effect that the shuttering side faces 42 are spaced apart from theshuttering support. In the embodiment described, e.g. four support unitscan be provided at each corner of the shuttering means which hasessentially the shape of a parallelepiped. The shuttering means can thusbe moved easily and rapidly to the desired position. When the desiredposition has been reached, the shuttering means will be lowered togetherwith the magnetic device, which is fixedly retained in the shutteringmeans. Hence, also the shuttering side faces will rest on the shutteringsupport at the position of use. For releasing the shuttering means, alift-off means, which is not shown and which may e.g. be an eccentric,can be provided. This eccentric can project e.g. centrally from thebottom side 4 of the magnetic device 2 and it can operable in the mannerknown via a lever extending through the shuttering means. It is thuspossible to use both shuttering side faces 42 for producing respectiveshutterings.

FIGS. 25 and 26 show enlarged representations of a retaining device andof a support unit of the type used e.g. in an embodiment according toFIG. 1. An adjusting screw 45 is here additionally provided whose bottomside 46 is fixed to the spring 24 by means of an adhesive. The adjustingscrew 45 is rotatably and adjustably received in an adjusting thread 47.By rotating the adjusting screw, the pretension of the spring 24 can bevaried. For this purpose, the rest-on means 14 is again captivelyaccommodated in the retaining device. By rotating the adjusting screw45, the distance between the bottom side of the adjusting screw 45 andthe rest-on surface can be varied so that the pretension of the spring24 will change. In the representation in FIG. 26, it can easily be seenthat a small gap between the retaining device and the shuttering supportremains at the position of use. Since the magnetic device rests fully onthe shuttering support, a redundancy in determination of the contactbetween the magnet and the retaining device can be avoided.

FIGS. 27 and 28 show a further embodiment of the retaining device and ofthe support unit in accordance with the representation shown in FIGS. 25and 26. In the case of this embodiment, the spring 24 is provided withthreaded portions 48 at the respective ends thereof, said threadedportions 48 being screwed into threads 49 and 50 in the retaining deviceand in the rest-on means 14. By rotating the rest-on means 14, it isagain possible to vary the distance between the rest-on means 14 and theretaining device 12 and thus the pretension of the spring.

1. A positioning aid for a magnetic device used for positioning at leastone of a shuttering means and shuttering elements, the magnetic devicebeing movable between a position of use, in which said magnetic deviceis in contact with a ferromagnetic shuttering support, and a position ofnon-use, in which said magnetic device is spaced apart from theshuttering support, said positioning aid comprising at least oneretaining device relative to which the magnetic device is supportedagainst a holding force of said magnetic device, and further comprisingat least one resilient support unit for producing a lifting forceagainst said holding force so as to hold the magnetic device in theposition of non-use, wherein the magnetic device is firmly connected tothe retaining device and that, at least in the position of non-use, thesupport unit is arranged between the retaining device and the shutteringsupport, at least along certain sections thereof.
 2. A positioning aidaccording to claim 1, wherein at least two spaced-apart retainingdevices are provided, which each have associated therewith one supportunit.
 3. A positioning aid according to claim 2, wherein the retainingdevices are arranged on opposed sides of the magnetic device.
 4. Apositioning aid according to claim 2, wherein four retaining devices areprovided.
 5. A positioning aid according to claim 1, wherein theretaining device comprises one of two respective retaining devicesassociated with one side of the magnetic device.
 6. A positioning aidaccording to claim 1, wherein the retaining device comprises one of aplurality of retaining devices that are interconnected such that theyare adapted to be moved to spaced-apart positions via associatedadjusting means.
 7. A positioning aid according to claim 1, wherein theretaining device comprises a first retaining device rigidlyinterconnected to a second retaining device.
 8. A positioning aidaccording to claim 6, wherein the retaining devices, together with theadjusting means, form a holding frame which surrounds the magneticdevice.
 9. A positioning aid according to claim 1, wherein the retainingdevice is releasably connected to the magnetic device.
 10. A positioningaid according to claim 1, wherein the magnetic device has essentiallythe shape of a parallelepiped and a bottom side thereof faces theshuttering support.
 11. A positioning aid according to claim 1, whereinthe retaining device is adapted to be attached to one of the side facesof the magnetic device.
 12. A positioning aid according to claim 1,wherein the retaining device is attached to an upper side of themagnetic device, said upper side facing away from the shutteringsupport.
 13. A positioning aid according to claim 1, wherein theretaining device includes a reception means which is engaged by themagnetic device.
 14. A positioning aid according to claim 13, whereinthe magnetic device is adapted to be inserted into said reception means.15. A positioning aid according to claim 1, wherein the retaining deviceis attached to the magnetic device by a screw connection.
 16. Apositioning aid according to claim 1, wherein a lift-off means isprovided with the aid of which the magnetic device can be transferredfrom its position of use to its position of non-use.
 17. A positioningaid according to claim 16, wherein the lift-off means is attached to themagnetic device.
 18. A positioning aid according to claim 16, whereinthe lift-off means is provided with an eccentric which is adapted to bebrought into engagement with the shuttering support, so as to effect amovement from the position of use to the position of non-use.
 19. Apositioning aid according to claim 18, wherein a lever is provided foroperating the lift-off means.
 20. A positioning aid according to claim19, wherein the lever and the eccentric are firmly interconnected androtatably supported on the magnetic device.
 21. A positioning aidaccording to claim 18, wherein the eccentric is arranged such that it islocated closer to one side of the magnetic device than to the sidelocated opposite said first-mentioned side.
 22. A positioning aidaccording to claim 1, wherein the support unit is provided with anelastic spring element for producing the lifting force.
 23. Apositioning aid according to claim 22, wherein the elastic springelement is a compression spring.
 24. A positioning aid according toclaim 22, wherein the elastic spring element comprises an elastomer. 25.A positioning aid according to claim 22, wherein the elastic springelement is a rubber element.
 26. A positioning aid according to claim22, wherein the elastic spring element is a plastic spring.
 27. Apositioning aid according to claim 22, wherein the elastic springelement is a bending sheet whose end portion is adapted to be deflectedby sliding on the shuttering support during the transfer movement.
 28. Apositioning aid according to claim 22, wherein the support unit includesa rest-on means, which is displaceably supported in the retaining deviceand which rests on the shuttering support at least at the position ofnon-use, the spring element being accommodated between the rest-on meansand the retaining device.
 29. A positioning aid according to claim 28,wherein the rest-on means is substantially pot shaped and that thereception means of the retaining device has the shape of a cylinderjacket.
 30. A positioning aid according to claim 28, wherein the rest-onmeans is captively connected to the retaining device.
 31. A positioningaid according to claim 22, wherein the spring force of the springelement is adjustable.
 32. A positioning aid according to claim 31,wherein an adjusting screw is provided for adjusting the spring force.33. A positioning aid according to claim 32, wherein the spring elementis provided with an adjusting thread.
 34. A positioning aid according toclaim 1, wherein the retaining device is integrated in the magneticdevice.
 35. A positioning aid according to claim 24, wherein theretaining device is formed by holes in the magnetic device.
 36. Apositioning aid according to claim 1, wherein the retaining device isconnected to the magnetic device by an adhesive.